Terrain Modifiers
- Plains
- mag = 80, speed = 16.5
- Highland
- mag = 100, speed = 20
- Mountain
- mag = 120, speed = 25
Higher mag = more attacker losses; higher speed = slower advance. Mountains are hardest to crack, plains are easiest. v24 added "terrain manipulation" allowing limited modification of adjacent tile terrain.
Defense Posts
mag ×5, speed ×3—a single DefensePost can turn plains into effective mountains. 1-2 posts at chokepoints (straits, isthmuses) can hold off an entire opponent.
Large Army Penalty (Defender)
- Plains terrain
- mag = 80, speed = 16.5
- Highland terrain
- mag = 100, speed = 20
- Mountain terrain
- mag = 120, speed = 25
- Defense Post bonus
- Within 30 tiles: mag ×5, speed ×3
- Fallout-zone penalty
- mag *= (5 - falloutRatio × 2)
- Large-army sigmoid penalty
- defenseSig = 1 - sigmoid(defender.tiles, ln(2)/50000, 150000)
- Betrayal penalty
- Defense ×0.5, Speed ×0.8, duration 300 ticks (30s)
- Large-attacker bonus
- When tiles > 100k: bonus = (100k/tiles)^0.7
Key constant: DEFENSE_DEBUFF_MIDPOINT = 150,000 tiles. As defender tiles approach or exceed this, defense decays from 1.0 to 0.7:
- 50k tiles: almost no decay.
- 150k tiles: half decay (midpoint).
- 300k tiles: approaching minimum 0.7×.
This is OpenFront's core "no permanent superpower" mechanic—grow too large and you can't push or hold.
Large Army Bonus (Attacker)
When attacker tiles > 100k: bonus = (100k / tiles)^0.7. Gives large powers slight marginal push advantage to pressure smaller opponents, while maxTroops doesn't explode.
Betrayal Debuffs
Attacking an ally = entering betrayer state:
- Defense ×0.5 (you take more damage)
- Advance speed ×0.8
- Lasts 300 ticks (30 seconds)
- Triggers auto-embargo from target + entire map
Therefore "betrayal rush" must either kill in 30 seconds (capture their core cities) or don't start.
Population & Attack
- Population cap base
- 2 × (0.6 × tiles^0.6 × 1000 + 50,000) + Σ(cityLevel × 250,000)
- Population type multiplier
- Human ×1 / Bot ÷3 / Nation Easy ×0.5, Med ×0.75, Hard ×1, Imp ×1.25
- Troop growth rate
- toAdd = (10 + troops^0.73 / 4) × (1 - troops / maxTroops)
Simplified takeaways:
- Low population (troops < 30% maxTroops) grows extremely fast—expand aggressively.
- High population (troops > 80% maxTroops) growth nearly stops—attack immediately or build City to raise maxTroops.
Naval Combat
- Warship HP 1000, auto-retreats to port for repair at ≤750 HP.
- Shell damage 250, 3 hits kill a full-health warship.
- v24 warships prioritize transport ships, cooldown resets on hit—one patrolling warship can wipe an entire landing fleet.
Combat Checklist
- 📍 Check terrain before attacking: target plains edges.
- 🏰 Check enemy DefensePosts: if covering chokepoint, find another route.
- 📊 Compare tiles: you 100k vs them 200k means you get attacker bonus while their defense is decayed; head-on actually favors you.
- 🤝 Don't betray: unless you can kill them in 30 seconds, betrayal usually hurts you more.